To be truly pedantic: there is no single international standard[1] of "high speed" rail, but in general, new lines up to 155mph, or upgraded lines up to 125mph,

To be truly pedantic: there is no single international standard[1] of "high speed" rail, but in general, new lines up to 155mph, or upgraded lines up to 125mph, are usually considered "high speed". In the United States, "higher-speed" rail has been the term used for trains up to 125mph.[2] [1] https://en.wikipedia.org/wiki/High-speed_rail#Definitions https://en.wikipedia.org/wiki/High-speed_rail#Definitions [2] https://en.wikipedia.org/wiki/Higher-speed_rail https://en.wikipedia.org/wiki/Higher-speed_rail